Currently, research and development of an SiC (Silicon Carbide) device are done in many research institutions. As a characteristic of the SiC devices, it can be mentioned of low on resistance, high speed switching, high temperature operation, etc.
Conventionally, since the temperature span which can operate in Si devices, such as IGBTs (Insulated Gate Bipolar Transistors), currently used in the field of a semiconductor power module is to about 150 degrees C., it was possible to have driven even when using low melting point solder, such as a conventional Sn—Ag alloy system.
However, since the SiC devices can theoretically operate to about 400 degrees C., if the SiC devices are driven at high temperature when using the conventional low melting point solder, the short circuit between electrodes, the delamination between the SiC devices and a base plate, etc. occurred by fusing bonding parts when using the low melting point solder, and then the reliability of the SiC devices are spoiled.
Accordingly, the SiC devices could not be driven at high temperature, and the characteristic of the SiC devices was not able to be used.
It is already disclosed about an interconnection method of the SiC device, and a low thermal resistance package (for example, refer to Patent Literature 1 and Patent Literature 2). In Patent Literature 1 and Patent Literature 2, a fabrication method of the package housing the SiC device is disclosed, and the SiC device is bonded for other parts or conductive surfaces using TLP bonding technology.
The TLP technology currently disclosed in the literatures is the technology for bonding the SiC device by fabricating high temperature melting point bonding using the mixed crystal of three kinds or four kinds of conductive metals fabricated simultaneously. Since the TLP bonding of three kinds or four kinds of metallic materials is used as a result, the components of the mixed crystal of the conductive metal are complicated.
On the other hand, it is already disclosed about a compound solder article whose melting point is comparatively low (for example, the melting point is not more than 430 degrees C.) including Sn and/or Pb (for example, refer to Patent Literature 3). In Patent Literature 3, the solder alloy has a smaller difference in temperature of the liquid phase and solid phase than that of the basic solder.
Furthermore, it is already disclosed also about transfer of metal MEMS packages using a wafer-level solder transfer technology (for example, refer to Non Patent Literature 1). In Non Patent Literature 1, a device wafer and a package cap are bonded by TLP technology using relatively thin Ni—Sn layer.